This invention relates generally to electronically controlled sewing machines and, more particularly to an improved device for limiting the maximum temperature of electronic components therein.
Presently in electronically controlled sewing machines, the electronic components are carried on a plurality of circuit boards supported in the sewing machine frame in specific relation to mechanical or electromechanical components from which they derive information or to which they supply information in the form of electrical signals. Thus, a circuit board which may support a solid state memory and pulse generating components to signal the release of information from the solid state memory would be located adjacent a cam device for initiating pulses supported on the horizontal armshaft of the sewing machine. The power amplifiers and heat sink for the power transistors of the power amplifiers may be carried on a second board in a position where a heat sink for the power transistors may be firmly attached to the sewing machine frame, thereby used as an additional heat sink. Additional circuit boards are required to carry components accessible to a sewing machine operator for selective variation of the sewing parameters or function.
In addition, appearance design of present day household sewing machines favors a clean, uncluttered look, best and most economically achieved by having a sewing machine frame with as few openings as possible, particularly in the front facing a machine operator. Such a design requires considerable resourcefulness in placement of electronic, mechanical and electromechanical components in view of the limited access to the interior of the frame, which is normally not consonant with mass production of a sewing machine.
Lastly, favored Engineering design of sewing machine requires separation of function and control whereby a sewing machine may be assembled with all the required functional components prior to addition of, or interchange of, a control package assembly which may be modified, or added to, to reflect the latest marketing considerations.
What is required is a heat sink arrangement for a sewing machine with a frame having the above noted limited access, which will readily receive or release a heat sink member supporting heat generating devices part of an electronic control package assembly for installation or replacement thereof. Advantageously, the heat sink arragement should make of the sewing machine frame an additional heat sink while also providing support for the electronic control package assembly.